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From: Paolo Bonzini <pbonzini@redhat.com>
To: Jing Liu <jing2.liu@linux.intel.com>,
	seanjc@google.com, kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, jing2.liu@intel.com
Subject: Re: [PATCH RFC 3/7] kvm: x86: XSAVE state and XFD MSRs context switch
Date: Mon, 8 Feb 2021 11:25:07 +0100	[thread overview]
Message-ID: <ae5b0195-b04f-8eef-9e0d-2a46c761d2d5@redhat.com> (raw)
In-Reply-To: <20210207154256.52850-4-jing2.liu@linux.intel.com>

On 07/02/21 16:42, Jing Liu wrote:
> |In KVM, "guest_fpu" serves for any guest task working on this vcpu 
> during vmexit and vmenter. We provide a pre-allocated guest_fpu space 
> and entire "guest_fpu.state_mask" to avoid each dynamic features 
> detection on each vcpu task. Meanwhile, to ensure correctly 
> xsaves/xrstors guest state, set IA32_XFD as zero during vmexit and vmenter.|

Most guests will not need the whole xstate feature set.  So perhaps you 
  could set XFD to the host value | the guest value, trap #NM if the 
host XFD is zero, and possibly reflect the exception to the guest's XFD 
and XFD_ERR.

In addition, loading the guest XFD MSRs should use the MSR autoload 
feature (add_atomic_switch_msr).

Paolo


  parent reply	other threads:[~2021-02-08 10:38 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-07 15:42 [PATCH RFC 0/7] Introduce support for guest AMX feature Jing Liu
2021-02-07 15:42 ` [PATCH RFC 1/7] kvm: x86: Expose XFD CPUID to guest Jing Liu
2021-05-24 21:34   ` Sean Christopherson
2021-06-07  3:27     ` Liu, Jing2
2021-02-07 15:42 ` [PATCH RFC 2/7] kvm: x86: Introduce XFD MSRs as passthrough " Jing Liu
2021-05-24 21:43   ` Sean Christopherson
2021-05-24 21:57     ` Jim Mattson
2021-06-02  3:12     ` Liu, Jing2
2021-06-23 17:50     ` Dave Hansen
2021-06-28  2:00       ` Liu, Jing2
2021-06-29 17:58         ` Dave Hansen
2021-07-06  7:33           ` Liu, Jing2
2021-02-07 15:42 ` [PATCH RFC 3/7] kvm: x86: XSAVE state and XFD MSRs context switch Jing Liu
2021-02-07 11:49   ` Borislav Petkov
2021-02-08  3:35     ` Liu, Jing2
2021-02-08 10:25   ` Paolo Bonzini [this message]
2021-02-08 17:31     ` Sean Christopherson
2021-02-08 17:45       ` Paolo Bonzini
2021-02-08 18:04         ` Sean Christopherson
2021-02-08 18:12           ` Paolo Bonzini
2021-02-08 18:55             ` Konrad Rzeszutek Wilk
2021-02-22  8:51               ` Liu, Jing2
2021-02-22  8:36             ` Liu, Jing2
2021-02-07 15:42 ` [PATCH RFC 4/7] kvm: x86: Add new ioctls for XSAVE extension Jing Liu
2021-05-24 21:50   ` Sean Christopherson
2021-05-26  6:09     ` Liu, Jing2
2021-05-26 14:43       ` Sean Christopherson
2021-06-01 10:24         ` Liu, Jing2
2021-06-07  5:23           ` Liu, Jing2
2021-05-24 22:06   ` Jim Mattson
2021-05-26  6:11     ` Liu, Jing2
2021-02-07 15:42 ` [PATCH RFC 5/7] kvm: x86: Revise CPUID.D.1.EBX for alignment rule Jing Liu
2021-05-24 21:28   ` Sean Christopherson
2021-06-03  4:45     ` Liu, Jing2
2021-02-07 15:42 ` [PATCH RFC 6/7] kvm: x86: Add AMX_TILE, AMX_INT8 and AMX_BF16 support Jing Liu
2021-02-07 15:42 ` [PATCH RFC 7/7] kvm: x86: AMX XCR0 support for guest Jing Liu
2021-05-24 21:53   ` Sean Christopherson
2021-05-26  7:54     ` Liu, Jing2
2021-05-26 14:54       ` Sean Christopherson

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